FF3.1beta3 in Peacekeeper performance test

Hi,

I follow the impressive performance improvements of FF very closely, but 
today I saw a new performance test which I could not believe.
http://www.futuremark.com/pressroom/pressreleases/55300/

"..Peacekeeper measures your browser's performance by testing its 
JavaScript functionality. ..."

The following features are tested:
http://service.futuremark.com/peacekeeper/faq.action

As result they show this
http://www.heise.de/mobil/Neuer-Benchmark-fuer-Internetbrowser--/zoom/134567/0

which means that FF 3.1b3 is only ~1/2 as fast as safari 4.0

I tried this test on my mac pro (2,4ghz, 4gb) and I got the following 
results:
Safari 3.2.1   791points
FF3.1beta3     592points

Has anyone an explaination why FF3.1 performs so poor in this test, 
because sofar I saw only tests where FF3.1 was only faster or fast as 
chrome.

Regards,
Mike